Railroad Truck Providing Improved Dynamic Characteristics Of The Freight Railway Car And The Railroad Truck Components

ABSTRACT

An novel railway car truck comprising side frames with vertical columns and bolster openings, a central swing suspension, a bolster, side bearers, and friction shock absorber friction wedges that has an improved dynamic performance facilitated by a novel central swing suspension set of springs and/or a novel design of the friction shock absorber friction wedges and/or a novel design of the side bearings.

BACKGROUND OF THE INVENTION

The proposed technical solutions relate to the railway vehicles,especially to the railroad truck design that provides high dynamiccharacteristics of the freight railway car that meets the respectiverequirements of the Association of American Railroads' standards.

The dynamic characteristics of a railway car are determined, in manyrespects, by the parameters of its truck components, specifically, bythe design of friction shock absorbers, the dimensions and performanceof central swing suspension springs and the mechanical features of truckbolster side bearers.

The central swing suspension includes friction shock absorbers, eachcontaining a pair: friction wedge-friction pad, and a set of springsmade of composite two-row compression springs supporting the bolster andfriction wedges.

The dynamic performance of freight railway car and its impact on therailway track are described with two key indicators: the designdeflection safety factor Kres of central swing suspension set of springsand the relative friction coefficient φ (φ—“Relative frictioncoefficient”), which describes the efficiency of railway car body shockabsorption by the friction shock absorber.

With inefficient shock absorption, resonance swaying of the railway carbody may occur, i.e. the design deflection safety factor Kres isinadequate. With excessive shock absorption, which occurs when Kresvalue is high, the friction shock absorber rubbing parts may get lockedas the railway car suspension becomes blocked with the impact on therailway track increased.

The physical sense of the design deflection safety factor Kres ofcentral swing suspension springs is to demonstrate the spring deflectionsafety before any undesirable contact of the central swing suspensionspring working coils in all possible regular operation modes of freightrailway car. The central swing suspension spring flexibility, in thiscase, must be the highest provided the maximum allowable verticalmovement of the springs under compression.

The required resistance to the freight railway car body verticalvibration is created by friction forces resulting from the relativemovement of friction shock absorber parts rubbing between themselves inthe pair “friction wedge-friction pad”. The friction forces betweenthose parts have relative friction coefficient «qp». Coefficient «qp»must ensure effective reduction vibration amplitude of the freightrailway car body with the highest possible central swing suspensionspring flexibility when the conditions of allowable vertical movement oflongitudinal axles of couplers of adjacent railway cars are met.

The railroad truck side bearers take forces resulting from the freightrailway car body pivot pitch and transmit them to the bolster. Properlyselected springing element of the side bearers ensure effective bodyshock absorption and improve the freight railway car dynamiccharacteristics.

With the purpose of improving the freight railway car dynamiccharacteristics, a great number of railroad truck designs have beendeveloped.

Some of the most common trucks with an axial load of 32.5 tf are MotionControl trucks manufactured by Amsted Rail. Also, are known thefollowing truck technical solutions with a swing suspension system madeof S-335-compliant springs: U.S. Pat. No. 7,174,837 B2, Three-piecemotion control truck system; Pub. No.: US 2013/0056919 A1, Dampingdevice. The main disadvantage of these trucks is that their dynamiccharacteristics poorly match the respective requirements of theAssociation of American Railroads' standards.

BRIEF SUMMARY OF THE INVENTION

The needs of an improved railway car truck, which comprises side frameswith vertical columns and bolster openings, a central swing suspension,a bolster, side bearers, friction shock absorber friction wedges are metthrough the present invention, which, in one embodiment, describes acentral swing suspension set of springs that boosts the truck's dynamicperformance.

In another embodiment of the present invention, the dynamic performanceof the railway car truck is improved by the described design of thefriction shock absorber friction wedge of the railway car truck.

In yet another aspect of the present invention, the dynamic performanceof the railway car truck is improved by the described design of the sidebearings of the railway car truck.

In yet another embodiment of the present invention, the foregoingcomponents are utilized in combinations for their complementarybenefits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: proposed freight railway car truck, general view.

FIG. 2: bolster of the proposed railroad truck, general view.

FIG. 3: detail A from FIG. 1, showing the railroad truck componentarrangement in the bolster opening.

FIG. 4: friction wedge of the friction shock absorber, isometric view.

FIG. 5: same as above, front view.

FIG. 6: same as above, side view.

FIG. 7: section B B from FIG. 6.

FIGS. 8, 9: detail «C» from FIG. 7, showing examples of the intermediatesection implementation at the friction wedge of the friction shockabsorber.

FIG. 10: illustration of the friction shock absorber friction wedgeposition within the railroad truck, isometric view, the bolster isomitted for clarity.

FIG. 11: central swing suspension set of springs located under thebolster and under the friction wedges, conventional diagram.

FIG. 12: central swing suspension spring deflection dependency graphsfor the proposed and different other railroad trucks.

FIG. 13: central swing suspension set of springs work dependency graphsfor different implementations of h/H ratio for the proposed railroadtruck.

FIGS. 14, 15, 16: implementation examples railroad truck side bearerswith different springing element configuration options.

DETAILED DESCRIPTION

The railroad truck has side frames 1, bolster 2 (FIG. 1). Each sideframe 1 is equipped with vertical columns 1.1 and bolster opening 3.

On bolster 2 end parts 2.1, guiding pockets 2.2 are implemented withsloping bearing surfaces 2.3 (FIG. 2).

On the side frame 1 vertical columns 1.1, the friction shock absorberfriction pads 4 are fastened (FIG. 3). On bolster opening 3 bearingsurface 3.1, the central swing suspension springing elements are locatedand made as a set of springs consisting of two concentrically arrangedcompression springs. Bolster 2 with its end parts 2.1 and the frictionshock absorber friction wedges 5 rest on the respective springs.

Friction wedge 5 (FIG. 4) is implemented as a single hollow body withsloping front bearing surfaces 5.1, rear wall with flat surface 5.2,designed for friction engagement with friction pad 4 mating surface.Flat base 5.3 is designed to interact with upper ends of springs 8 and 9(FIG. 11).

The front wall is implemented as two front bearing surfaces 5.1 slopingat an angle α to the base 5.3 and at an angle 2β to each other, designedto interact with mating bearing surfaces 2.3 of bolster 2 guidingpockets 2.2.

Front bearing sloping surfaces 5.1 in their bottom side part and base5.3 of friction wedge 5 may be implemented with the respective recessesM to place in them the upper ends of outer springs 6.

The friction force arising between sloping bearing surfaces 2.3 ofbolster 2 guiding pockets 2.2 and sloping front bearing surfaces 5.1 ofthe friction shock absorber friction wedges 5 in the proposed railroadtruck is 2-3 times less than the friction force arising between flatsurface 5.2 of friction wedges 5 rear wall and the mating surfaces offriction pad 4 fastened on the side frame 1 vertical columns 1.1.

Friction pads 4 are implemented with height ‘a’ in 245-260 mm range andtheir contact surface roughness of Rz40 to Rz80 ensuring frictioncoefficient fN=0.38 between friction pads 4 and flat surface 5.2 offriction wedges 5 rear wall. Height ‘b’ of each friction pad 4 loweredge position in reference to bearing surface 3.1 of side frame 1bolster opening 3 is implemented in 160-175 mm range.

Ensuring friction wedge 5 contact on its entire flat surface 5.2 withfriction pad 4 surface results in a uniform wear of friction wedge 5 andfriction pad 4 contacting surfaces due to implementation of thefollowing parameters:

-   -   height ‘a’ of friction pad 4 should be maintained within 245-260        mm range;    -   height ‘b’ of friction pad 4 lower edge position in reference to        bearing surface 3.1 of side frame 1 bolster opening 3 should be        maintained within 160-175 mm range.

The selection of above ranges ‘a’ and ‘b’ is governed by the centralswing suspension spring deflection values to ensure friction wedge 5rear wall contact on its entire flat surface 5.2 with friction pad 4.With empty freight railway car, the full-scale deflection f1 of centralswing suspension set of springs equals 25 mm; with loaded car thefull-scale deflection f2 of central swing suspension set of springsequals 83 mm.

Full contact of friction wedge 5 rear wall flat surface 5.2 withfriction pad 4 of empty car is ensured at height ‘a’ value of more than160 mm Full contact of friction wedge 5 rear wall flat surface 5.2 withfriction pad 4 of loaded car is ensured at height ‘a’ value of less than175 mm.

The increase of contact area of “friction wedge-friction pad” paircontacting surfaces required to enhance the efficient freight railwaycar body shock absorption can be reached at height ‘b’ value of morethan 245 mm. The uniform wear of friction pad 4 contacting surface isensured at height ‘b’ value of less than 260 mm, because the highestfull-scale deflection of the central swing suspension set of springsunder freight railway car gross weight will ensure reaching by frictionwedge 5 of friction pad 4 lower edge.

The selection of friction pad 4 height ‘a’ is made based on thecondition:

a≥c+f2,

where:

c height of friction wedge 5;

f2—full-scale deflection of central swing suspension set of springs inloaded freight railway car.

If a, b, f2 values get into the boundary values of their respectiveallowable ranges, it is guaranteed that the contact area of “frictionwedge-friction pad” pair remains constant in the empty and loaded modesof operation.

The sloping front bearing surfaces 5.1 are inclined at an angle α to thebase 5.3 (FIGS. 5, 6) and at an angle 2β to each other (FIG. 7).

In order to ensure a highly effective relative friction coefficient φwithin the desired ranges (between 0.1 and 0.4 for empty railway car andbetween 0.07 and 0.13 for loaded railway car) the values of angles α and2β must stay in the following ranges:

-   -   angle α within 50° to 65° range for the empty and loaded railway        car, respectively;    -   angle 2β within 130° to 150° range for the empty and loaded        railway car, respectively.

For effective interaction between friction wedge 5 and sloping bearingsurfaces 2.3 of bolster 2 guiding pockets 2.2, contact area Z isimplemented on sloping front bearing surfaces 5.1. The contact area Z ismade with 1.0-5.0 mm deep thermal quenching, up to 350-450 HB hardnessand with roughness of Rz 40 to Rz 80 to ensure friction coefficientfN=0.15 between the surface of contact area Z and sloping bearingsurfaces 2.3 of bolster 2 guiding pockets 2.2. Width hz of contact areaZ is 37-99 mm. In reference to base 5.3, the middle of contact area Z isat a distance ‘e’ equaling 68 mm assumed the centerline z-z of contactarea Z.

Flat surface 5.2 of friction wedge 5 rear wall designed to interact withfriction pad 4 contact surface is implemented with roughness of Rz 40 toRz 80 to ensure friction coefficient fN=0.38 between flat surface 5.2and friction pads 4.

The implementation of friction shock absorber friction wedges 5 andfriction pads 4 with the above parameters ensures that the frictionforce difference between sloping bearing surfaces 2.3 of bolster 2guiding pockets 2.2 and sloping front bearing surfaces 5.1 of frictionwedges 5 is 2-3 times less than the friction force arising between flatsurface 5.2 of friction wedges 5 rear wall and friction pads 4 to ensureimprovement of the freight railway car dynamic characteristics.

On the front wall of friction wedge 5, between sloping front bearingsurfaces 5.1, intermediate section 5.4 may be implemented (FIG. 6) toensure contact of sloping bearing surfaces 2.3 with sloping frontbearing surfaces 5.1.

Intermediate section 5.4, in its longitudinal direction, may beimplemented with convex surface with radial distance R maintained in 650to 920 mm range. Such implementation of intermediate section 5.4provides more accurate and fluid mutual setting and interaction offriction wedge 5 and bolster 2 mating surfaces. Such fluid interfacingalso improves the freight railway car dynamic characteristics.

Intermediate section 5.4, in its cross-section, may be implemented withan inner arc-like surface with radius r (FIG. 8) or an inner angle (FIG.9). In the first embodiment, intermediate section 5.4 may have radius rin 10 to 50 mm range and depth hl in 2 to 8 mm range. In the secondembodiment, intermediate section 5.4 may have width ‘s’ in 10 to 50 mmrange and depth hl in 2 to 8 mm range.

Width W of friction wedge 5 may be between 155 and 175 mm. This range ofwidth W was chosen based on the condition of free positioning offriction wedge 5 in bolster 2 guiding pockets 2.2, as well as on thecondition of optimal mounting of guiding pockets 2.2 on bolster 2 endparts 2.1. Height c of friction wedge 5 is between 135 and 160 mm.

Friction wedge 5 shown in FIG. 10 in assembly with side frame 1 providesthrough its recesses M the free positioning of outer springs 6 underbolster 2. In addition, between the surfaces of recesses M and outersprings 6 an operating clearance is provided.

The dynamic characteristics of the freight railway car depend, in manyrespects, on the performance of the springs in the central swingsuspension set of springs. The improvement of railway car dynamiccharacteristics can be accomplished by selecting the optimal parametersof the central swing suspension set of springs.

The central swing suspension set of springs, which support bolster 2(FIG. 11), is made of composite two-row coil compression springs withouter springs 6 and inner springs 7 located under end parts 2.1 ofbolster 2. The central swing suspension set of springs also includescomposite two-row compression springs made of outer springs 8 and innersprings 9 located under friction wedges 5 (hereinafter referred to as“underwedge springs”).

The height of each underwedge outer spring 8 is less than the height ofunderwedge inner spring 9 by a value of 6 to 10 mm.

To ensure that the design deflection safety factor Kres of central swingsuspension set of springs is between 1.50 and 1.75, the ratio of height‘h’ of each inner spring 7 from the set of springs for placing underbolster 2 to height ‘H’ of each underwedge inner spring 9 must be within0.90 to 0.95 range. In this case, the height ‘h’ of inner spring 7 isless than the height of outer spring 6 within 2 to 6 mm range; theheight of underwedge outer spring 8 is less than the height ofunderwedge inner spring 9 by a value within 6 to 10 mm range.

The two-row springs under the friction wedges are implemented with totalstiffness of 353.7 kN/m; in addition, each outer spring 8 is implementedwith outer diameter d8 of 123 to 125 mm, free height h8 of 282 to 286mm, has stiffness of 251.4 kN/m and is made of a rod with diameter d8 of20.5 to 21.5 mm; each inner spring 9 is implemented with outer diameterd9 of 78 to 80 mm, free height h9 of 290 to 294 mm, has stiffness of102.3 kN/m and is made of a rod with diameter d9 of 13 to 14 mm.

The two-row springs under the bolster are implemented with totalstiffness of 531.6 kN/m; in addition, each outer spring 6 is implementedwith outer diameter d6 of 138 to 142 mm, free height h6 of 273 to 277mm, has stiffness of 354.3 kN/m and is made of a rod with diameter d6 of23 to 25 mm; each inner spring 7 is implemented with outer diameter d7of 88 to 90 mm, free height h7 of 271 to 275 mm, has stiffness of 177.3kN/m and is made of a rod with diameter d7 of 15 to 17 mm.

In the Table below, spring parameters are listed as an example ofimplementation of the central swing suspension compression springs withthe stated parameters.

TABLE PARAMETERS OF THE CENTRAL SWING SUSPENSION SPRINGS Type of Springouter inner Parameter Parameter under- under- Description Identifierouter inner wedge wedge Modulus of G 80000 elasticity, MPa Rod d 24.016.0 21.0 13.5 diameter, mm Spring outer D 140.0 89.0 124.0 79.0diameter, mm Free height, mm H 275.0 273.0 284.0 292.0 Active coils n6.00 9.50 7.08 11.35

The implementation where the underwedge outer spring 8 height is lessthan the underwedge inner spring 9 height by an amount within 6 to 10 mmrange results in:

-   -   increase the wear margin of friction wedge 5, its contraction        ratio to guiding pocket 2.2 of bolster 2,    -   improve the vibration damping of empty freight railway car,        thereby ensuring improvement of its dynamic properties.

If the height difference between underwedge springs 8 and 9 is more than10 mm, this will lead to a decrease of their deflection safety and,accordingly, under the car gross weight load, closing of coils ofunderwedge springs 8 and 9 may occur.

If the height difference between underwedge springs 8 and 9 is less than6 mm, this will lead to increase of their stiffness, rise of verticalaccelerations and, as a result, to decrease of the safety factor ofrailroad truck against derailment.

If the ratio of minimum height spring 6 or 7 from the set of springs forplacing under bolster 2 to maximum height spring 8 or 9 from the set ofunderwedge springs is less than 0.90, then deflection of underwedgesprings 8, 9 increases with simultaneous decrease of the deflectionsafety factor resulting in a shorter service life of the central swingsuspension springs.

If the above ratio is more than 0.95, this will result in decrease ofdeflection for empty car and friction wedge 5 contraction ratio, thusworsening the vibration damping of the freight railway car anddecreasing the wear margin of friction wedge 5 rubbing surfaces.

If the design deflection safety factor Kres of central swing suspensionsprings is less than 1.5, this will lead to a decrease of deflectionreserve before the closing the working coils of central swing suspensionsprings and, as a result, to loss of their strength. In addition, withhigh amplitudes of freight railway car body vibration, an increase ofthe vertical dynamics coefficient will cause closing of most springworking coils and their cutoff, which will result in shock impact on therailway track.

Use of springs with the design deflection safety factor Kres of centralswing suspension springs less than 1.75 will lead, with the limited sizeof bolster opening 3.1 and due to large stiffness of the springs, toemergence of large accelerations under conditions when the freightrailway car runs on uneven sections of railway track, which will resultin increase of vibration frequency of the freight railway car and inworsening of its stability.

FIG. 12 shows graphs comparing the central swing suspension springdeflection versus applied load of the proposed truck New bogie (line C),Motion Control Bogie suspension with D-5 spring (line B) and Bogie18-100 Russia (Line A).

The graph analysis reveals that when the central swing suspensionsprings simultaneously come into operation, the graph lines sharplyincrease indicating that the set of springs reach the empty railway carmode with slight spring deflection. This does not provide the emptyfreight railway car with the vertical travel reserve, which causes largedynamic forces on the suspension and the freight railway car structures,leading to large dynamic impact on the railway track and a possibilityof the empty car derailment.

Graph C, illustrating the work of proposed set of springs, reveals thatsequential placement in operation of the central swing suspensionsprings facilitates sooner placement in operation of the friction wedge(areas 1-2) ensuring its optimal operation, and after subsequentplacement in operation of the springs located under the bolster (areas2-3), the central swing suspension set of springs reaches the workingmode of operation with the last, shortest, springs placed in operationbefore reaching the loaded railway car mode. Such a displacement ofgraph C to the right from zero ensures an increase of the deflectionsafety and spring travel for empty car while maintaining the frictionshock absorber efficient operation. The increased travel reserve forempty car guarantees the optimal dynamic properties while ensuring thenecessary spring deflection safety for loaded car.

To ensure the optimal dynamic properties, the ratio of height ‘h’ ofinner springs 7 placed under bolster 2 to height ‘H’ of underwedge innersprings 9 is within 0.90 to 0.95 range. This ratio ensures that evenbefore springs 6, 7 located under bolster 2 start working, underwedgesprings 8, 9 will be placed in operation sooner, which guaranteesconstant pressing of friction wedge 5 to friction pad 4.

FIG. 13 shows deflection dependency of the central swing suspension setof springs for different implementations of h/H ratio. Line C1illustrates deflection versus the central swing suspension spring loadswith h/H ratio equal 0.95. Line C2 illustrates deflection versus thecentral swing suspension spring load with h/H ratio equal 0.90. LineCavg illustrates mean value of the claimed range.

Areas 1-2-3 (FIG. 13) reflect the guaranteed constant pressing offriction wedge 5 to friction pad 4. In this case, the heights ofunderwedge springs 8 and 9 have been chosen in such a manner that, whensprings 6, 7 are placed in operation, including at the start ofoperation for the empty mode, the required pressing of friction wedge 5to friction pad 4 is assured, which allows for the friction shockabsorber to provide effective damping of car body vertical vibrations.

The claimed h/H ratio within 0.90 to 0.95 range and selection of springs6, 7 ensure that the value of the design deflection safety factor Kresof central swing suspension springs is in 1.50 and 1.75 range. In turn,this ensures increased deflection safety of the central swing suspensionsprings under static and dynamic operating loads including dynamicloading, which in the physical sense means a lesser contraction ratio ofsprings. This leads to a lesser deformation of spring coils, drop ofstress and, as a result, to improvement of the coil reliability,increase of their service life, decrease of dynamic loads, improvementof empty car's vibration damping and to its high dynamic properties.

In the first area of the graph, from 0 to point 1 (line Cavg), onlyunderwedge inner springs 9 work; the full-scale deflection f1 of centralswing suspension equals 8 mm.

In the second area of the graph, between points 1 and 2, friction wedges5 bias against both inner 9, and outer 8 underwedge springs. In area0-2, the values of full-scale deflections f 9-2 and f 8-2 of inner 9 andouter 8 underwedge springs are: f 9-2=17 mm and f 8-2=9 mm.

In the third area, from point 2 to point 3, between points 2 and 3,outer springs 6 located under bolster 2 begin operating. In area 0-3,the values of full-scale deflections f 9-3 and f 8-3 of inner 9 andouter 8 underwedge springs are: f 9-3=19 mm, f 8-3=11 mm; the value offull-scale deflection f 6-3 of outer spring 6 located under bolster 2is: f 6−3=2 mm.

In the fourth area, inner springs 7 located under bolster 2 beginoperating, in addition, all springs from the central swing suspensionset of springs also begin operating.

The ratio of maximum height of springs 6, 7 located under bolster totheir minimum height is within 0.90 to 0.95. This helps to maintainstrength and reliability of the springs under static and dynamicoperating loads.

A major contribution to obtaining optimal dynamic performance of thefreight railway car is provided by the railroad truck side bearers.Properly selected design and matching springs of side bearers exert asignificant impact on the improvement of this performance.

Side bearer 10 (FIG. 14) of the railroad truck has a carrier body 10.1with base 10.2 and a lead hole, in which, with the assistance ofspringing element 11, stop sleeve 12 with its deflecting wall isspringingly installed.

Springing element 11 may be implemented as a single compression spring11.1 or made of multiple compression springs 11.2, 11.3, 11.4, 11.5,11.6 (FIGS. 15, 16).

For use under a car with the least tare weight of 18 t, springingelement 11 may be implemented as a single spring 11.1 (FIG. 14). In thiscase, spring 11.1 has stiffness of 564.22 kN/m and is made of a rod withdiameter d1 of 19.5 to 20.5 mm, with an outer diameter Dout1 of 117.5 to118.5 mm, with a free height of 134 to 138 mm.

With car tare weight of at least 22 t for truck side bearers springingelement 11 may be used with total stiffness of 824.64 kN/m, made of twocompression springs 11.2 and 11.3 located one inside the other (FIG.15). In this case, outer spring 11.2 has stiffness of 564.22 kN/m and ismade of a rod with a diameter d2 of 19.5 to 20.5 mm, with an innerdiameter Din2 of 77.5 to 78.5 mm, with a free height of 134 to 138 mm;inner spring 11.3 is implemented with stiffness of 260.42 kN/m and ismade of a rod with diameter d3 of 12.7 to 13.4 mm, with an outerdiameter Dout3 of 69.3 to 70.4 mm and with a free height of 134 to 138mm.

For car tare weight of at least 25 t for truck side bearers springingelement 11 may be used with total stiffness of 1073 kN/m, made of threecompression springs 11.4, 11.5, 11.6 (FIG. 16). In this case, outerspring 11.4 has stiffness of 662.95 kN/m and is made of a rod with adiameter d4 of 20.5 to 21.6 mm, with an inner diameter Din4 of 76.4 to77.5 mm, with a free height of 131 to 135 mm; middle spring 11.5 hasstiffness of 307.36 kN/m and is made of a rod with a diameter d5 of 13.6to 14.7 mm, with an outer diameter Dout5 of 74.6 to 75.7 mm, with a freeheight of 131 to 135 mm; inner spring 11.6 has stiffness of 102.6 kN/mand is made of a rod with a diameter d6 of 8.0 to 8.3 mm, with an outerdiameter Dout6 of 42.9 to 43.2 mm and a free height of 131 to 135 mm.

The ranges described in the foregoing paragraphs are provided in thecontext of certain embodiments. The described ranges and may bedifferent for alternative embodiments or if non-standard materials orrailcar designs are used.

On the inner surface of the stop sleeve 12 of the railroad truck sidebearers, intermediate support plate 13 may be placed for use insupporting springing elements 11 and protecting stop sleeve 12 innersurface from wear.

Consequently, the proposed technical solutions for the group ofinventions within the railroad truck and its components significantlyimprove the freight railway car dynamic properties to ensure compliancewith the requirements of the Association of American Railroads'standards.

While at least one exemplary embodiment of the present invention(s) isdisclosed herein, it should be understood that modifications,substitutions and alternatives may be apparent to one of ordinary skillin the art and can be made without departing from the scope of thisdisclosure. This disclosure is intended to cover any adaptations orvariations of the exemplary embodiment(s). In addition, in thisdisclosure, the terms “comprise” or “comprising” do not exclude otherelements or steps, the terms “a” or “one” do not exclude a pluralnumber, and the term “or” means either or both. Furthermore,characteristics or steps which have been described may also be used incombination with other characteristics or steps and in any order unlessthe disclosure or context suggests otherwise.

What is claimed is:
 1. A railway truck comprising: a first sideframe anda second sideframe distanced from the first sideframe, the sideframesincluding: an opening including a vertical column and a bearing surface;a spring assembly disposed on the bearing surface; a bolster having twomating sections at opposite ends, wherein each of the mating sectionsincludes a sloped pocket, wherein one of the mating sections is disposedwithin the opening of the first sideframe and the other mating sectionis disposed within the opening of the second sideframe; a firstsideframe friction wedge disposed within the opening of the firstsideframe and a second sideframe friction wedge disposed within theopening of the second sideframe, the friction wedges including: a slopedside engageable with the sloped pocket of the bolster mating section; avertical side engageable with vertical column of the bolster opening; aside supportable by the spring assembly; wherein the frictioncoefficient of the engagement between the vertical side of the wedge andthe vertical column is two to three times greater than the frictioncoefficient of the engagement between the sloped side of the wedge andthe sloped pocket.
 2. The railway truck of claim 1 wherein the slopedside of the friction wedges comprises at least two front bearingsurfaces that are at an angle between 130 degrees and 150 degrees toeach other.
 3. The railway truck of claim 1 wherein the sloped side ofthe friction wedges is at an angle between 50 degrees and 65 degrees tothe side supportable by the spring assembly of the friction wedges. 4.The railway truck of claim 1 wherein the sloped side of the frictionwedges comprises two front bearing surfaces that are at an angle to oneanother and are arc shaped.
 5. The railway truck of claim 1 wherein eachvertical column comprises a friction pad and the friction pad has asurface roughness between Rz 40 and Rz
 80. 6. The railway truck of claim1 wherein each vertical column comprises a friction pad and the frictionpad has a vertical height between 245 millimeters and 260 millimetersand wherein the pocket comprises an insert that interfaces with thewedge.
 7. The railway truck of claim 1 wherein the sloped side of thefriction wedges comprises two front bearing surfaces that are at anangle to one another and an intermediate front section between the twofront bearing surfaces, the intermediate front section having a convexsurface with a radius between 650 millimeters and 920 millimeters in theplane between the two front bearing surfaces.
 8. The railway truck ofclaim 1 wherein the sloped side of the friction wedges comprises twofront bearing surfaces that are at an angle to one another and anintermediate front section between the two front bearing surfaces, theintermediate front section defining a recess.
 9. A railway truckcomprising: a first sideframe and a second sideframe distanced from thefirst sideframe, the sideframes including: an opening including avertical column and a bearing surface; a spring assembly with adeflection safety factor between 1.5 and 1.75 disposed on the bearingsurface; a bolster having two mating sections at opposite ends, whereineach of the mating sections includes a sloped pocket, wherein one of themating sections is disposed within the opening of the first sideframeand the other mating section is disposed within the opening of thesecond sideframe; a first sideframe friction wedge disposed within theopening of the first sideframe and a second sideframe friction wedgedisposed within the opening of the second sideframe.
 10. The railwaytruck of claim 9, wherein each spring assembly comprises at least onewedge spring configured to support the corresponding friction wedge,wherein the at least one wedge spring includes an outer spring and aninner spring; and wherein the uncompressed height of the wedge springouter spring is between 6 millimeters and 10 millimeters less than anuncompressed height of the wedge spring inner spring.
 11. The railwaytruck of claim 9, wherein each spring assembly comprises at least onewedge spring configured to support the corresponding friction wedge andthe wedge spring has a total stiffness of 353.7 KN/m.
 12. The railwaytruck of claim 9, wherein each spring assembly comprises at least onewedge spring configured to support the corresponding friction wedge andat least one bolster spring configured to support the correspondingbolster mating section, wherein the ratio of an uncompressed height ofthe bolster spring to an uncompressed height of the wedge spring isbetween 0.9 and 0.95.
 13. The railway truck of claim 9, wherein thefirst and second friction wedges include: a sloped side engageable withthe sloped pocket of the bolster mating section; a vertical sideengageable with vertical column of the bolster opening; a sidesupportable by the spring assembly; wherein the friction coefficient ofthe engagement between the vertical side of the wedge and the verticalcolumn is two to three times greater than the friction coefficient ofthe engagement between the sloped side of the wedge and the slopedpocket.
 14. A railway truck comprising: a first sideframe and a secondsideframe distanced from the first sideframe, the sideframes including:an opening; a bolster having two mating sections at opposite ends,wherein each of the mating sections includes a sloped pocket, whereinone of the mating sections is disposed within the opening of the firstsideframe and the other mating section is disposed within the opening ofthe second sideframe; a side bearer disposed on the bolster, the sidebearer including: a carrier body; a springing element disposed withinthe carrier body; a stop sleeve slidably engaged with the carrier body,the stop sleeve surrounding and supported by the springing element, and;wherein the springing element has a dynamic deflection safety of 16.6millimeters.
 15. The railway truck of claim 14, wherein the springingelement includes a plurality of concentric springs with springs withlarger diameters having higher stiffness than springs with smallerdiameters.
 16. The railway truck of claim 14, wherein the springingelement has a vertical stiffness between 564 kN/m and 1073 kN/m.
 17. Therailway truck of claim 14, further comprising a support plate disposedbetween the springing element and the sleeve.
 18. The railway truck ofclaim 14, wherein the opening of the first sideframe and opening of thesecond sideframe each further includes: a vertical column and a bearingsurface; a spring assembly disposed on the bearing surface; wherein thetruck further comprises a first sideframe friction wedge disposed withinthe opening of the first sideframe and a second sideframe friction wedgedisposed within the opening of the second sideframe, the friction wedgescomprising: a sloped side frictionally engageable with the sloped pocketof the bolster mating section; a vertical side frictionally engageablewith vertical column of the bolster opening; a side supportable by thespring assembly; wherein the friction coefficient of the engagementbetween the vertical side of the wedge and the vertical column is two tothree times greater than the friction coefficient of the engagementbetween the sloped side of the wedge and the sloped pocket.
 19. Therailway truck of claim 18, wherein the vertical side of each frictionwedge has a vertical height between 135 millimeters and 160 millimeters,and the vertical side of each friction wedge has a width between 155millimeters and 175 millimeters.